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Groups > linux.kernel > #1733640
| From | Huacai Chen <chenhc@lemote.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN in non-coherent DMA mode |
| Date | 2017-09-18 06:30 +0200 |
| Message-ID | <uqVR0-Xl-7@gated-at.bofh.it> (permalink) |
| Organization | linux.* mail to news gateway |
In non-coherent DMA mode, kernel uses cache flushing operations to maintain I/O coherency, so the dmapool objects should be aligned to ARCH_DMA_MINALIGN. Otherwise, it will cause data corruption, at least on MIPS: Step 1, dma_map_single Step 2, cache_invalidate (no writeback) Step 3, dma_from_device Step 4, dma_unmap_single If a DMA buffer and a kernel structure share a same cache line, and if the kernel structure has dirty data, cache_invalidate (no writeback) will cause data lost. Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen <chenhc@lemote.com> --- mm/dmapool.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/dmapool.c b/mm/dmapool.c index 4d90a64..6263905 100644 --- a/mm/dmapool.c +++ b/mm/dmapool.c @@ -140,6 +140,9 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, else if (align & (align - 1)) return NULL; + if (!device_is_coherent(dev)) + align = max_t(size_t, align, dma_get_cache_alignment()); + if (size == 0) return NULL; else if (size < 4) -- 2.7.0
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[PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN in non-coherent DMA mode Huacai Chen <chenhc@lemote.com> - 2017-09-18 06:30 +0200
Re: [PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN in non-coherent DMA mode Christoph Hellwig <hch@infradead.org> - 2017-09-18 07:30 +0200
Re: [PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN innon-coherent DMA mode "陈华才" <chenhc@lemote.com> - 2017-09-18 09:00 +0200
Re: [V5, 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN in non-coherent DMA mode Robin Murphy <robin.murphy@arm.com> - 2017-09-18 11:50 +0200
Re: [V5, 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN in non-coherent DMA mode Christoph Hellwig <hch@infradead.org> - 2017-09-18 18:00 +0200
Re: [V5, 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN innon-coherent DMA mode "陈华才" <chenhc@lemote.com> - 2017-09-19 04:30 +0200
Re: [PATCH V5 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN in non-coherent DMA mode Christoph Hellwig <hch@infradead.org> - 2017-09-18 17:50 +0200
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